The intense commercialization of metallocene polyolefin catalysts (metallocene being cyclopentadienyl based transition metal catalyst compounds) has led to widespread interest in the design of non-metallocene, homogeneous catalysts. This field is more than an academic curiosity as new, non-metallocene catalysts may provide an easier pathway to currently available products and may also provide product and process opportunities which are beyond the capability of metallocene catalysts. In addition, certain non-cyclopentadienyl ligands will be more economical due to the relative ease of synthesis of a variety of substituted analogs.
Anionic, multidentate heteroatom ligands have received the most attention in non-metallocene polyolefins catalysis. Notable classes of bidentate anionic ligands which form active polymerization catalysts include N--N.sup.- and N--O.sup.- ligand sets. Examples of these types of non-metallocene catalysts include amidopyridines (Kempe, R., "Aminopyridinato Ligands--New Directions and Limitations", 80.sup.th Canadian Society for Chemistry Meeting, Windsor, Ontario, Canada, Jun. 1-4, 1997. Kempe, R. et al, Inorg. Chem. 1996 vol 35 6742.) Likewise, recent reports by Jordan et al. of polyolefin catalysts based on hydroxyquinolines (Bei, X.; Swenson, D. C.; Jordan, R. F., Organometallics 1997, 16, 3282) have been interesting even though the catalytic activities of Jordan's hydroxyquinoline catalysts is low.
European Patent Application 0 803 520 discloses polymerization catalysts containing beta-diketiminate ligands. Other recent non-metallocene olefin polymerization catalysts include U.S. Pat. No. 4,057,565 which discloses 2-dialkylaminobenzyl and 2-dialkylaminomethylphenyl derivatives of selected transition metals and WO 96/08498 which discloses group 4 metal complexes containing a bridged non-aromatic, anionic dienyl ligand group.
U.S. Pat. No. 5,637,660 discloses bidentate pyridine based transition metal catalysts.
Further Grubbs et al in Organometallics, Vol 17, 1988 page 3149-3151 disclose that nickel (II) salicylaldiminato complexes combined with B(C.sub.6 F.sub.5).sub.3 polymerized ethylene. (49,500 Mw, Mw/Mn 6.8, and 35 branches per 1000 C's).
Ethylenebis(salicylideneiminato)zirconium dichloride combined with methyl alumoxane deposited on a support and unsupported versions were used to polymerize ethylene by Repo et al in Macromolecules 1997, 30, 171-175.
Further EP 241,560 A1 discloses alkoxide ligands in transition metal catalyst systems.
EP 0 874 005 A1 discloses phenoxide compounds with an imine substituent for use as a polymerization catalyst.
Thus there is a need in the art for new novel olefin polymerization catalysts.